Southwest and Alaska Air are nearing tests of a new ad-supported Wi-Fi system. The hardware and software are installed by third parties with the goal to point fliers to an online catalog called the Skytown Center.

Whether you purchased Wi-Fi or not, you could do some shopping on the plane (with the participating retailers and advertisers footing the bill.) But the more tempting benefit is that airlines look to have most or all the costs associated with providing in-flight Wi-Fi covered under such sponsorships. So while there's no guarantee we'll be browsing the entire web for free, it seems a likely scenario that you'll be able to check your email if you're willing to deal with a few extra ads.

The service, powered by JiWire, will be launching this fall. [Marketing Vox via Mashable via Lifehacker]

Southwest is using a satellite-based system from Row 44, and not the cellular connection used by most other airlines with Aircell's GoGo service. So if you find yourself on that one (and soon to be handful) of Row 44-equipped planes, you can surf for free. [USA Today]

Both Air Canada and Alaska are safe havens for unfettered access, at least for now. (VoIP is blocked though.)They're both holding off to see how things go without a content filter, and hope you read their terms of use. Virgin America is the best though, since they seem to be more philosophically opposed to a content filter than the others—their spokesperson said that they don't block content on their entertainment systems, so they plan to keep that in place for Wi-Fi.

Of course, no one can filter what you bring on the plane in your hard drive. And most airports have plenty of nudie magazines for sale all around the terminal. You know, if you're really that determined to look at boobs on a plane, but you could at least watch an arty movie with boobs to be somewhat less gauche. [MSBNC]